Thermally controlled switch and the like



Nov. 13, 1934. J D Ross 1,980,439

THERMALLY CONTROLLED SWITCH AND THE LIKE Original Filed March 13, 1928 i q I I :0 III IN VEN TOR.

7 ATTORNEYS.

Patented Nov. 13, 1934- PATENT THERMALLY CONTROLLED SWITCH AND THE LIKE Application March 13, 1928, Serial No. 261,227 Renewed January 16, 1932 1d Claims.

This invention relates to electric switches, and more particularly to switches which are thermostatic in character and have heat or pressure-responsive elements adapted to cooperate in controlling an electric circuit.

The object of the invention generally is to provide an electric switch of the character described which is efficient, economical and readily manufact-ured.

More specifically, the object is to provide a thermostatic switch which will open and close a circuit in a certain and reliable manner, the control parts of the switch. being substantially free 5 from arcing and arranged so that the switch may be adjusted to respond precisely within narrow ranges of variation in the condition to be controlled.

Other objects of the invention will in part be obvious and will in part appear hereinafter The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exempliiied in the construction hereinafter set forth and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in n connection with the accompanying drawing, in which:

Figure 1 is a plan view of an electric switch constructed in accordance with the present invention, but with the cover removed in order to 35 reveal the internal arrangement of parts;

Fig. 2 is a view, partially in side elevation and partially in section, showing the arrangement of the parts of the switch when viewed from the side;

Fig. 3 is a diagrammatic View showing the arrangement of the working parts employed in the switch in Fig. 1; and

Fig. 4 is a fragmentary detail View.

Referring now to the drawing, is denotes a base on which the parts of the switch of the present invention are mounted. This base may be of any suitable material, but is preferably of metal, since it can be readily molded to any desired shape. As shown, this base has an upstanding bead 11 of suitable depth that serves as a guide upon which to secure a casing or hous- 50 ing (not shown) for protecting the switch parts.

To support the switch parts properly upon the base 10, a pair of spaced plates 12 and 12', preferably of insulating material, are mounted upon the base. The spacing of the plates 12 and 12 is 55 here maintained by means of four interposed insulating posts 13 disposed therebetween. Between the plates 12 and 12 there is placed the main control element 14. This main control element is designed to be responsive to the condition which is to control the electric circuit to be made and broken by the switch of the present invention. This main control element may have any convenient form which is adapted to respond to the condition which is to be controlled. In the form here illustrated this main control element is shown as an expansible metallic bellows closed on one side but having a protuberance 15 adapted to bear against a downwardly projecting column 16 arranged to bear against and actuate a pivoted control contact arm, shown at 17.

The ezipansible bellows is here shown as also provided with a tubular connection 18 secured in the plate 12', which is adapted to be connected to a suitable source of pressure for actuating the expansible bellows. Such source is, for example a steam boiler, a steam radiator or an enclosed body of a heat-sensitive fluid such as alcohol, sulphuric ether and the like.

The main contacts for the switch are shown at 20, these contacts making and breaking the electric circuit which is to be controlled. One element of the contacts 20 is mounted on the stationary arm 21; the second element thereof being carried by the pivoted arm 22. This latter arm is shown as pivotally mounted in a support 23 secured on the plate 12. In order that there may be flexibility at the contact junction 20, the element carried by the arm 22, preferably has a flexible leaf-spring 24 extending from it to carry the contact element, this element having also attached thereto a flexible conductor 25 which leads to a suitable terminal 26 secured in the plate 12. The stationary arm 21 likewise has a terminal 2'7 electrically connected therewith and through which electrical connections are made to the other side of the contact junction at 20.

The movable arm 22, by its movement, controls the make-and-break of the electrical circuit at the contact junction 20. Movement of this arm however is accomplished by means of a toggle comprising the links 28-29, the link 28 being preferably a relatively short solid member, pivotally secured to a bifurcated standard 30 mounted on the top plate 12. (For convenience in assembly standard 30 and support 23 are preferably made integral.) The link 29, on the other hand, as shown in Fig. 1, is preferably in the form of a rectangular frame having side members which extend from each side of the link 28 for pivotal engagement with the sides of the arm 22, these side members being conveniently bent down out of the plane of a sheet of metal from which they are made so as to lie, when assembled in the switch, principally in planes which are perpendicular to the top plate 12. The sides of the link 29 are joined by an over-hung end 31 which extends across link 28 beyond the point at which the link 28 is pivoted to the link 29. This overhung portion 31 consequently serves as a stop to prevent the toggle from moving downward toward the plate 12, out of the horizontal position shown in Fig. 2. The toggle links 2829 thus can only move upwardly to open the contacts at 20. To effect this movement of the toggle links 2829, the control contact arm 17 is provided with an extension member 32 which has suf" ficient length to extend from the arm 17 to bear against link 28 at a point relatively close to its pivotal connection with the link 29. It is thus seen that an upward movement of the arm 1'? causes. a breaking of the toggle linkage a quickwithdrawal of the contact element by the movement of the arm 22.

jecting through the upper plate member Inordr' to close the toggle links 28-29 when broken, an electromagnet 33 is provided. The electromagnet shown is secured between the plates 12 and 12 and has a core member 34 pro-- 12 adapted to cooperate with an armature member 35 which is conveniently pivoted in the standard 30 below the toggle link 28, as shown in Fig. 4.

There is secured to the armature a flexible link 36 which extends up through the side members of the link 29 and has a laterally-extending engaging member 37 which engageswith upstanding projections 38 formed on the side members of the toggle link 29. The flexible link may be made out of any suitable material, but is preferably made out of a piece of resilient sheet metal, that is bent somewhat into an S -shape, as indicated, so that it may provide a link member readily yielding in length in the direction in which it transmits pull. By this arrangement, it is readily seen that when the magnet 33 is energized, it pulls downwardly upon the armature 35 which in turn transmits a pull through the link 36 to the engaging member 37 to draw down on the knee of the toggle linkage and push it into the horizontal position shown in Fig. 2. V

To energize the electromagnet' 33, an auxiliary circuit is provided in the switch structure which.

if desired, may be under the control not only of the main control element 14, but also of a control under the influence of local conditions. The arrangement of this control circuit will be more readily understood by reference to Fig. 3, where the connections thereof are symbolically indicated. Here the terminals 26 and 27 are shown as bridged by the main contacts at 26. These contacts areshown as connectedin series with a main electric circuit comprising the conductors 40 and 41 arranged to supply electric current to a current-consuming element 42. The control circuit in the switch is shown as connected across the terminals 26 and 27 in shunt with the main contacts at 20 through the winding of the electromagnet 33. shunt circuit comprises the conductor 43 connecting in series the terminal 26, the control contact arm 17, and contact member 44 with which the arm cooperates. This contact member is shown inv dotted lines in Fig. 1 and is mounted on a plate 45, the other end of which is mounted on and pivotally secured to the adjusting screw 46 turning in theinsulating plate 12. Thus, by turning the screw 46, which, as indicated in Fig. 2, is adapted for manual manipulation, the distance of the contact member 44 from the arm 17 may be regulated, and the degree of temperature or pressure at which the control contact arm 17 energizes the electrcmagnet 33 to close the main contacts 20, adjusted to correspond with any desired point.

The shunt circuit, in addition to the above, as indicated in Fig. 3, has connected in series therewith an adjustable contact post 47 which, as shown in Figs. 1 and 2, is adapted for manual manipulation to adjust the height from the plate 12 of a condition-responsive contact-making member 43, whichit carries. This member 48 is a conducting compound bar made from so-called thermostatic metal and is designed to make contact with a cooperating member 49 all in the shunt circuit and in series with the electromagnet 33. By manually manipulating the vertical adjustment of post 4'], the thermostatic member 48 and the member 49 may be adjusted to close at any desired local condition of temperature.

In order to adjust the main control element to open the switch at a desired high-temperature or pressure-condition it is made to react against a spring 50, the tension of which can be manually adjusted. For convenience, this spring is made to bear on arm 1'7, which through member 16 bears on the main control element 14. The adjustment or" the spring tension is secured by means of the thumb-screw shown at 51.

In order better to insure the quick opening of the main contacts at 20 a section of helical spring is shown as connected at'52 between a point on the plate 12 and the moving end of arm 22.

In operation it will be seen that when the pressure indicative of the upper limit of the condition y to be controlled has been reached in the main control element 14, it reacts against the spring 50 and pushes up the control contact arm 17, the tip 32 of the latter pressing upwardly at the knee of p however, will not energize the magnet 33 if the thermostatic member 48 be not also in contact with its'cooperating member 49. This relation is useful, since it would not be desired to have the element 42 resupplied with electric current even though the pressure indicative of its condition had fallen to the predetermined value at which the arm 17 makes contact with element 44, if the atmosphere above the switch were still heated to such an extent that no more heating from the element 42-was required. When, however, the atmosphere about the switch has been sufficiently cooled to permit the thermostatic member .48 to make contact at 49 (i. e., when the circuit is closed both at tie contact points 44 and 49) then the shunt control circuit through the electromagnet' 33 is energized and a'pull is transmitted through the link 36 to close the toggle links 28--29, thereby closing the main contacts at 20 to supply element 42 again with current. From this it is seen that both the high point and the low point at which the main circuit is controlled. can be adjusted; the respective adjustments being independent.

It will be seen also that by this arrangement the point of temperature at which the local control renders the closing of the main circuit inoperative is adjustable independently of high and low limits of the main control. Also it is seen that the current in the control circuit may be made as small as desired by suitably proportioning the parts. Consequently the opening of this circuit either by the arm 1''! or by the thermostatic member 48 will produce only substantially a minimum of arcing. When the local conditions are operative to open the contact at the thermostatic member 48, it is seen that the control circuit is thereby made dead when the control contact arm 17 moves to open the toggle links 28-29, so that arcing is avoided.

Since the control circuit is in shunt with the main contacts there is seen to be no danger of overheating the winding of the electromagnet due to the passing of the main current.

Since certain changes may be made in the above construction and difierent embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-magnet adapted to control a function of said movable element, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, and a main controlling device movable into a plurality of controlling positions and adapted to close said shunt circuit when in one position and to mechanically control another function of said movable element when in another position.

2. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-rnagnet adapted to move said movable element in at least one direction, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a local condition-responsive element in said shunt circuit, arranged to make and break the same, and a main controlling device movable into a plurality of controlling positions and adapted to control the making of said shunt circuit jointly with said local responsive element when in one of its controlling positions, and to impart direct movement to said movable element in another direction when in another controlling position.

3. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-magnet adapted to actuate said movable element to make the circuit, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a thermally-responsive element in said shunt circuit arranged to make and break the same, and an expansible device responsive to a main condition to be controlled movable into a plurality of controlling positions and adapted to control the making of said shunt circuit with said thermally-responsive element when in one of its cont-rolling positions, and to actuate said movable element through mechanical connections to break the circuit when in another controlling position.

4. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-magnet adapted to move said movable element in at least one direction, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a thermally-responsive make-andbreak device in said shunt circuit and in series with the same, a mechanical connection adapted to impart to said movable main circuit making and breaking element a movement the reverse of the actuating movement imparted by said electro-magnet, and a main controlling device movable into a plurality of controlling positions and adapted to make said shunt circuit when said thermally-responsive make-and-break device is in the make position, and to operate said mechanical connection and to break said shunt circuit when in another controlling position.

5. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-magnet adapted to control a function of said movable element, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a local thermally-responsive makeand-break device in said shunt circuit and in series with the same, a mechanical connection for controlling another function of said movable main circuit making and breaking element, and an expansible device movable into two controlling positions responsive to the limitsof a main condition to be controlled and connected in said shunt circuit in series with said local. thermally-responsive make-and-break device, whereby said devices jointly control the make of said shunt circuit when one limit of the condition to be controlled is reached, said expansible device being arranged solely to actuate said mechanical connection when the other limit of the condition to be controlled is reached.

6. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking ele ments, of an electro-magnet adapted to move said movable element in at least one direction, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a local thermally-responsive make-and-break device in said shunt circuit and in series with the same, a mechanical connection for actuating said movable main circuit making and breaking element in a direction the reverse of that imparted by said electro-magnet, an expansible device movable into two controlling positions responsive to the limits of a main condition to be controlled and connected in said shunt cir- I cuit in series with said local thermally-responsive make-and-break device whereby said devices jointly control the make of said shunt circuit when one limit of the condition to be controlled is reached, said expansible device being arranged movable element in at least one direction, a

shunt circuit about 'said main'circuit making and breaking elements having said electro-magnet in series therewith, a local thermally-responsive make-and-break device in said shunt circuit and in series with the same, a mechanical connection for actuating said movable main circuit making and breaking element in a direction difierent from that imparted by said electro-magnet, an expansible device movable into two controlling positions responsive to the limits of a main condition to be controlled and connected in said'shunt circuit in series with said local thermally-responsive make-and-break device whreby said devices jointly control the make of said shunt circuit when one limit of the condition to be controlled is reached, said expansible device being 7 arranged solely to actuate said mechanical connection when the other limit of the condition to be controlled is reached, and means for adjusting the temperature at which said local thermallyresponsive device makes said shunt circuit.

8. In an electric switch of the character described, the combination with relatively fixed and movable main circuit making and breaking elements, of an electro-magnet adapted to move said movable element in at least one direction, a shunt circuit about said main circuit making and breaking elements having said electro-magnet in series therewith, a local thermally-responsive make-and-break device in said shunt circuit and in series withthe same, a mechanical connection for moving said movable main circuit making and breaking element in another direction from that imparted by said electro-magnet, an expansible device movable into two controlling positions responsive to the limits of a main condition to be controlled and connected in said shunt circuit in series with said local thermally-responsive makeand-break device whereby said devices jointly control the make of said shunt circuit when one limit of the condition to be controlled is reached, said expansible device being arranged solely to actuate said mechanical connection when the other limit of the condition to be controlled is reached, means for adjusting the temperature at which said local thermally-responsive device makes said shunt circuit, and means for adjusting the limits of the condition to be controlled to which said expansible device responds.

9. In apparatus of the character described, in

combination, electric switching means; nieans'ineluding a pressure-responsive element for'me chanically openingsaid switching means,- and means including said pressure-responsive element and a temperature-responsive elementiorclosing said switching means upon release of said pressure-responsive element" and actuation of said temperature-responsive element.

10. In apparatus'of the character described, in combination, electric'switching means, means re-' sponsive to the application of pressure for mechanically opening said switching means, electromagnetic means including said pressure-responsive means and a temperature responsive means electrically connected in series for closing said switching means upon completion of the electrical connection through said pressure-responsive means and said temperature-responsive means.

11. In apparatus of the class described, in combination, switching means, a pressure responsive means, an over' centering device actuated in one direction by said pressure responsive means, and means including a temperature responsive elementfor moving said switching means into-an other position.

12. In apparatus of the character described, in

a combination, switching means, an over-centering device for controlling a function of said switching means, and a temperature responsive element for controlling another function of said switching means.

13. In apparatus of the character described, in combination, switching means, an over-centering device for controlling a function of said switching means, and a temperature responsive element for controlling another function of said switching means, pressure responsive means for controlling a function of said over-centering device.

14. In apparatus of the character described, in combination, an electrical switching mechanism, an over-centering device for 7 operating said switching mechanism, a pressure responsive means for causing said over-centering device to operate in one direction, and means including a temperature responsive element and said pressure responsive means for operating said overcentering device in the opposite direction.

JOHN D. ROSS. 

